37 U.S. Servicemembers Are Killed in Iraq During One Day

BAGHDAD, Iraq (CNN) -- Thirty Marines and a Navy corpsman were killed in a helicopter crash near Iraq's border with Jordan, bringing the number of U.S. troops killed Wednesday to 37 -- the deadliest day for U.S. forces since the start of the war in Iraq.

Four U.S. Marines were killed during combat in Iraq's Anbar province, and two U.S. soldiers were killed in attacks in the Baghdad area, according to the U.S. military. (Most based in Hawaii)

The cause of the chopper crash is under investigation, although it appears to be weather-related, according to Gen. John Abizaid, chief of U.S. Central Command.

It's a dangerous environment that we operate in Iraq, we all understand that, and again our condolences to the families”

— Gen. John Abizaid, chief of U.S. Central Command